arch/x86/kernel/machine_kexec_64.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * handle transition of Linux booting another kernel
   4  * Copyright (C) 2002-2005 Eric Biederman  <ebiederm@xmission.com>
   5  */
   6
   7 #define pr_fmt(fmt)     "kexec: " fmt
   8
   9 #include <linux/mm.h>
  10 #include <linux/kexec.h>
  11 #include <linux/string.h>
  12 #include <linux/gfp.h>
  13 #include <linux/reboot.h>
  14 #include <linux/numa.h>
  15 #include <linux/ftrace.h>
  16 #include <linux/io.h>
  17 #include <linux/suspend.h>
  18 #include <linux/vmalloc.h>
  19 #include <linux/efi.h>
  20
  21 #include <asm/init.h>
  22 #include <asm/tlbflush.h>
  23 #include <asm/mmu_context.h>
  24 #include <asm/io_apic.h>
  25 #include <asm/debugreg.h>
  26 #include <asm/kexec-bzimage64.h>
  27 #include <asm/setup.h>
  28 #include <asm/set_memory.h>
  29
  30 #ifdef CONFIG_ACPI
  31 /*
  32  * Used while adding mapping for ACPI tables.
  33  * Can be reused when other iomem regions need be mapped
  34  */
  35 struct init_pgtable_data {
  36         struct x86_mapping_info *info;
  37         pgd_t *level4p;
  38 };
  39
  40 static int mem_region_callback(struct resource *res, void *arg)
  41 {
  42         struct init_pgtable_data *data = arg;
  43         unsigned long mstart, mend;
  44
  45         mstart = res->start;
  46         mend = mstart + resource_size(res) - 1;
  47
  48         return kernel_ident_mapping_init(data->info, data->level4p, mstart, mend);
  49 }
  50
  51 static int
  52 map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p)
  53 {
  54         struct init_pgtable_data data;
  55         unsigned long flags;
  56         int ret;
  57
  58         data.info = info;
  59         data.level4p = level4p;
  60         flags = IORESOURCE_MEM | IORESOURCE_BUSY;
  61
  62         ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
  63                                   &data, mem_region_callback);
  64         if (ret && ret != -EINVAL)
  65                 return ret;
  66
  67         /* ACPI tables could be located in ACPI Non-volatile Storage region */
  68         ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
  69                                   &data, mem_region_callback);
  70         if (ret && ret != -EINVAL)
  71                 return ret;
  72
  73         return 0;
  74 }
  75 #else
  76 static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }
  77 #endif
  78
  79 #ifdef CONFIG_KEXEC_FILE
  80 const struct kexec_file_ops * const kexec_file_loaders[] = {
  81                 &kexec_bzImage64_ops,
  82                 NULL
  83 };
  84 #endif
  85
  86 static int
  87 map_efi_systab(struct x86_mapping_info *info, pgd_t *level4p)
  88 {
  89 #ifdef CONFIG_EFI
  90         unsigned long mstart, mend;
  91
  92         if (!efi_enabled(EFI_BOOT))
  93                 return 0;
  94
  95         mstart = (boot_params.efi_info.efi_systab |
  96                         ((u64)boot_params.efi_info.efi_systab_hi<<32));
  97
  98         if (efi_enabled(EFI_64BIT))
  99                 mend = mstart + sizeof(efi_system_table_64_t);
 100         else
 101                 mend = mstart + sizeof(efi_system_table_32_t);
 102
 103         if (!mstart)
 104                 return 0;
 105
 106         return kernel_ident_mapping_init(info, level4p, mstart, mend);
 107 #endif
 108         return 0;
 109 }
 110
 111 static void free_transition_pgtable(struct kimage *image)
 112 {
 113         free_page((unsigned long)image->arch.p4d);
 114         image->arch.p4d = NULL;
 115         free_page((unsigned long)image->arch.pud);
 116         image->arch.pud = NULL;
 117         free_page((unsigned long)image->arch.pmd);
 118         image->arch.pmd = NULL;
 119         free_page((unsigned long)image->arch.pte);
 120         image->arch.pte = NULL;
 121 }
 122
 123 static int init_transition_pgtable(struct kimage *image, pgd_t *pgd)
 124 {
 125         pgprot_t prot = PAGE_KERNEL_EXEC_NOENC;
 126         unsigned long vaddr, paddr;
 127         int result = -ENOMEM;
 128         p4d_t *p4d;
 129         pud_t *pud;
 130         pmd_t *pmd;
 131         pte_t *pte;
 132
 133         vaddr = (unsigned long)relocate_kernel;
 134         paddr = __pa(page_address(image->control_code_page)+PAGE_SIZE);
 135         pgd += pgd_index(vaddr);
 136         if (!pgd_present(*pgd)) {
 137                 p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
 138                 if (!p4d)
 139                         goto err;
 140                 image->arch.p4d = p4d;
 141                 set_pgd(pgd, __pgd(__pa(p4d) | _KERNPG_TABLE));
 142         }
 143         p4d = p4d_offset(pgd, vaddr);
 144         if (!p4d_present(*p4d)) {
 145                 pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
 146                 if (!pud)
 147                         goto err;
 148                 image->arch.pud = pud;
 149                 set_p4d(p4d, __p4d(__pa(pud) | _KERNPG_TABLE));
 150         }
 151         pud = pud_offset(p4d, vaddr);
 152         if (!pud_present(*pud)) {
 153                 pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
 154                 if (!pmd)
 155                         goto err;
 156                 image->arch.pmd = pmd;
 157                 set_pud(pud, __pud(__pa(pmd) | _KERNPG_TABLE));
 158         }
 159         pmd = pmd_offset(pud, vaddr);
 160         if (!pmd_present(*pmd)) {
 161                 pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
 162                 if (!pte)
 163                         goto err;
 164                 image->arch.pte = pte;
 165                 set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
 166         }
 167         pte = pte_offset_kernel(pmd, vaddr);
 168
 169         if (sev_active())
 170                 prot = PAGE_KERNEL_EXEC;
 171
 172         set_pte(pte, pfn_pte(paddr >> PAGE_SHIFT, prot));
 173         return 0;
 174 err:
 175         return result;
 176 }
 177
 178 static void *alloc_pgt_page(void *data)
 179 {
 180         struct kimage *image = (struct kimage *)data;
 181         struct page *page;
 182         void *p = NULL;
 183
 184         page = kimage_alloc_control_pages(image, 0);
 185         if (page) {
 186                 p = page_address(page);
 187                 clear_page(p);
 188         }
 189
 190         return p;
 191 }
 192
 193 static int init_pgtable(struct kimage *image, unsigned long start_pgtable)
 194 {
 195         struct x86_mapping_info info = {
 196                 .alloc_pgt_page = alloc_pgt_page,
 197                 .context        = image,
 198                 .page_flag      = __PAGE_KERNEL_LARGE_EXEC,
 199                 .kernpg_flag    = _KERNPG_TABLE_NOENC,
 200         };
 201         unsigned long mstart, mend;
 202         pgd_t *level4p;
 203         int result;
 204         int i;
 205
 206         level4p = (pgd_t *)__va(start_pgtable);
 207         clear_page(level4p);
 208
 209         if (sev_active()) {
 210                 info.page_flag   |= _PAGE_ENC;
 211                 info.kernpg_flag |= _PAGE_ENC;
 212         }
 213
 214         if (direct_gbpages)
 215                 info.direct_gbpages = true;
 216
 217         for (i = 0; i < nr_pfn_mapped; i++) {
 218                 mstart = pfn_mapped[i].start << PAGE_SHIFT;
 219                 mend   = pfn_mapped[i].end << PAGE_SHIFT;
 220
 221                 result = kernel_ident_mapping_init(&info,
 222                                                  level4p, mstart, mend);
 223                 if (result)
 224                         return result;
 225         }
 226
 227         /*
 228          * segments's mem ranges could be outside 0 ~ max_pfn,
 229          * for example when jump back to original kernel from kexeced kernel.
 230          * or first kernel is booted with user mem map, and second kernel
 231          * could be loaded out of that range.
 232          */
 233         for (i = 0; i < image->nr_segments; i++) {
 234                 mstart = image->segment[i].mem;
 235                 mend   = mstart + image->segment[i].memsz;
 236
 237                 result = kernel_ident_mapping_init(&info,
 238                                                  level4p, mstart, mend);
 239
 240                 if (result)
 241                         return result;
 242         }
 243
 244         /*
 245          * Prepare EFI systab and ACPI tables for kexec kernel since they are
 246          * not covered by pfn_mapped.
 247          */
 248         result = map_efi_systab(&info, level4p);
 249         if (result)
 250                 return result;
 251
 252         result = map_acpi_tables(&info, level4p);
 253         if (result)
 254                 return result;
 255
 256         return init_transition_pgtable(image, level4p);
 257 }
 258
 259 static void load_segments(void)
 260 {
 261         __asm__ __volatile__ (
 262                 "\tmovl %0,%%ds\n"
 263                 "\tmovl %0,%%es\n"
 264                 "\tmovl %0,%%ss\n"
 265                 "\tmovl %0,%%fs\n"
 266                 "\tmovl %0,%%gs\n"
 267                 : : "a" (__KERNEL_DS) : "memory"
 268                 );
 269 }
 270
 271 int machine_kexec_prepare(struct kimage *image)
 272 {
 273         unsigned long start_pgtable;
 274         int result;
 275
 276         /* Calculate the offsets */
 277         start_pgtable = page_to_pfn(image->control_code_page) << PAGE_SHIFT;
 278
 279         /* Setup the identity mapped 64bit page table */
 280         result = init_pgtable(image, start_pgtable);
 281         if (result)
 282                 return result;
 283
 284         return 0;
 285 }
 286
 287 void machine_kexec_cleanup(struct kimage *image)
 288 {
 289         free_transition_pgtable(image);
 290 }
 291
 292 /*
 293  * Do not allocate memory (or fail in any way) in machine_kexec().
 294  * We are past the point of no return, committed to rebooting now.
 295  */
 296 void machine_kexec(struct kimage *image)
 297 {
 298         unsigned long page_list[PAGES_NR];
 299         void *control_page;
 300         int save_ftrace_enabled;
 301
 302 #ifdef CONFIG_KEXEC_JUMP
 303         if (image->preserve_context)
 304                 save_processor_state();
 305 #endif
 306
 307         save_ftrace_enabled = __ftrace_enabled_save();
 308
 309         /* Interrupts aren't acceptable while we reboot */
 310         local_irq_disable();
 311         hw_breakpoint_disable();
 312
 313         if (image->preserve_context) {
 314 #ifdef CONFIG_X86_IO_APIC
 315                 /*
 316                  * We need to put APICs in legacy mode so that we can
 317                  * get timer interrupts in second kernel. kexec/kdump
 318                  * paths already have calls to restore_boot_irq_mode()
 319                  * in one form or other. kexec jump path also need one.
 320                  */
 321                 clear_IO_APIC();
 322                 restore_boot_irq_mode();
 323 #endif
 324         }
 325
 326         control_page = page_address(image->control_code_page) + PAGE_SIZE;
 327         memcpy(control_page, relocate_kernel, KEXEC_CONTROL_CODE_MAX_SIZE);
 328
 329         page_list[PA_CONTROL_PAGE] = virt_to_phys(control_page);
 330         page_list[VA_CONTROL_PAGE] = (unsigned long)control_page;
 331         page_list[PA_TABLE_PAGE] =
 332           (unsigned long)__pa(page_address(image->control_code_page));
 333
 334         if (image->type == KEXEC_TYPE_DEFAULT)
 335                 page_list[PA_SWAP_PAGE] = (page_to_pfn(image->swap_page)
 336                                                 << PAGE_SHIFT);
 337
 338         /*
 339          * The segment registers are funny things, they have both a
 340          * visible and an invisible part.  Whenever the visible part is
 341          * set to a specific selector, the invisible part is loaded
 342          * with from a table in memory.  At no other time is the
 343          * descriptor table in memory accessed.
 344          *
 345          * I take advantage of this here by force loading the
 346          * segments, before I zap the gdt with an invalid value.
 347          */
 348         load_segments();
 349         /*
 350          * The gdt & idt are now invalid.
 351          * If you want to load them you must set up your own idt & gdt.
 352          */
 353         native_idt_invalidate();
 354         native_gdt_invalidate();
 355
 356         /* now call it */
 357         image->start = relocate_kernel((unsigned long)image->head,
 358                                        (unsigned long)page_list,
 359                                        image->start,
 360                                        image->preserve_context,
 361                                        sme_active());
 362
 363 #ifdef CONFIG_KEXEC_JUMP
 364         if (image->preserve_context)
 365                 restore_processor_state();
 366 #endif
 367
 368         __ftrace_enabled_restore(save_ftrace_enabled);
 369 }
 370
 371 /* arch-dependent functionality related to kexec file-based syscall */
 372
 373 #ifdef CONFIG_KEXEC_FILE
 374 void *arch_kexec_kernel_image_load(struct kimage *image)
 375 {
 376         vfree(image->elf_headers);
 377         image->elf_headers = NULL;
 378
 379         if (!image->fops || !image->fops->load)
 380                 return ERR_PTR(-ENOEXEC);
 381
 382         return image->fops->load(image, image->kernel_buf,
 383                                  image->kernel_buf_len, image->initrd_buf,
 384                                  image->initrd_buf_len, image->cmdline_buf,
 385                                  image->cmdline_buf_len);
 386 }
 387
 388 /*
 389  * Apply purgatory relocations.
 390  *
 391  * @pi:         Purgatory to be relocated.
 392  * @section:    Section relocations applying to.
 393  * @relsec:     Section containing RELAs.
 394  * @symtabsec:  Corresponding symtab.
 395  *
 396  * TODO: Some of the code belongs to generic code. Move that in kexec.c.
 397  */
 398 int arch_kexec_apply_relocations_add(struct purgatory_info *pi,
 399                                      Elf_Shdr *section, const Elf_Shdr *relsec,
 400                                      const Elf_Shdr *symtabsec)
 401 {
 402         unsigned int i;
 403         Elf64_Rela *rel;
 404         Elf64_Sym *sym;
 405         void *location;
 406         unsigned long address, sec_base, value;
 407         const char *strtab, *name, *shstrtab;
 408         const Elf_Shdr *sechdrs;
 409
 410         /* String & section header string table */
 411         sechdrs = (void *)pi->ehdr + pi->ehdr->e_shoff;
 412         strtab = (char *)pi->ehdr + sechdrs[symtabsec->sh_link].sh_offset;
 413         shstrtab = (char *)pi->ehdr + sechdrs[pi->ehdr->e_shstrndx].sh_offset;
 414
 415         rel = (void *)pi->ehdr + relsec->sh_offset;
 416
 417         pr_debug("Applying relocate section %s to %u\n",
 418                  shstrtab + relsec->sh_name, relsec->sh_info);
 419
 420         for (i = 0; i < relsec->sh_size / sizeof(*rel); i++) {
 421
 422                 /*
 423                  * rel[i].r_offset contains byte offset from beginning
 424                  * of section to the storage unit affected.
 425                  *
 426                  * This is location to update. This is temporary buffer
 427                  * where section is currently loaded. This will finally be
 428                  * loaded to a different address later, pointed to by
 429                  * ->sh_addr. kexec takes care of moving it
 430                  *  (kexec_load_segment()).
 431                  */
 432                 location = pi->purgatory_buf;
 433                 location += section->sh_offset;
 434                 location += rel[i].r_offset;
 435
 436                 /* Final address of the location */
 437                 address = section->sh_addr + rel[i].r_offset;
 438
 439                 /*
 440                  * rel[i].r_info contains information about symbol table index
 441                  * w.r.t which relocation must be made and type of relocation
 442                  * to apply. ELF64_R_SYM() and ELF64_R_TYPE() macros get
 443                  * these respectively.
 444                  */
 445                 sym = (void *)pi->ehdr + symtabsec->sh_offset;
 446                 sym += ELF64_R_SYM(rel[i].r_info);
 447
 448                 if (sym->st_name)
 449                         name = strtab + sym->st_name;
 450                 else
 451                         name = shstrtab + sechdrs[sym->st_shndx].sh_name;
 452
 453                 pr_debug("Symbol: %s info: %02x shndx: %02x value=%llx size: %llx\n",
 454                          name, sym->st_info, sym->st_shndx, sym->st_value,
 455                          sym->st_size);
 456
 457                 if (sym->st_shndx == SHN_UNDEF) {
 458                         pr_err("Undefined symbol: %s\n", name);
 459                         return -ENOEXEC;
 460                 }
 461
 462                 if (sym->st_shndx == SHN_COMMON) {
 463                         pr_err("symbol '%s' in common section\n", name);
 464                         return -ENOEXEC;
 465                 }
 466
 467                 if (sym->st_shndx == SHN_ABS)
 468                         sec_base = 0;
 469                 else if (sym->st_shndx >= pi->ehdr->e_shnum) {
 470                         pr_err("Invalid section %d for symbol %s\n",
 471                                sym->st_shndx, name);
 472                         return -ENOEXEC;
 473                 } else
 474                         sec_base = pi->sechdrs[sym->st_shndx].sh_addr;
 475
 476                 value = sym->st_value;
 477                 value += sec_base;
 478                 value += rel[i].r_addend;
 479
 480                 switch (ELF64_R_TYPE(rel[i].r_info)) {
 481                 case R_X86_64_NONE:
 482                         break;
 483                 case R_X86_64_64:
 484                         *(u64 *)location = value;
 485                         break;
 486                 case R_X86_64_32:
 487                         *(u32 *)location = value;
 488                         if (value != *(u32 *)location)
 489                                 goto overflow;
 490                         break;
 491                 case R_X86_64_32S:
 492                         *(s32 *)location = value;
 493                         if ((s64)value != *(s32 *)location)
 494                                 goto overflow;
 495                         break;
 496                 case R_X86_64_PC32:
 497                 case R_X86_64_PLT32:
 498                         value -= (u64)address;
 499                         *(u32 *)location = value;
 500                         break;
 501                 default:
 502                         pr_err("Unknown rela relocation: %llu\n",
 503                                ELF64_R_TYPE(rel[i].r_info));
 504                         return -ENOEXEC;
 505                 }
 506         }
 507         return 0;
 508
 509 overflow:
 510         pr_err("Overflow in relocation type %d value 0x%lx\n",
 511                (int)ELF64_R_TYPE(rel[i].r_info), value);
 512         return -ENOEXEC;
 513 }
 514 #endif /* CONFIG_KEXEC_FILE */
 515
 516 static int
 517 kexec_mark_range(unsigned long start, unsigned long end, bool protect)
 518 {
 519         struct page *page;
 520         unsigned int nr_pages;
 521
 522         /*
 523          * For physical range: [start, end]. We must skip the unassigned
 524          * crashk resource with zero-valued "end" member.
 525          */
 526         if (!end || start > end)
 527                 return 0;
 528
 529         page = pfn_to_page(start >> PAGE_SHIFT);
 530         nr_pages = (end >> PAGE_SHIFT) - (start >> PAGE_SHIFT) + 1;
 531         if (protect)
 532                 return set_pages_ro(page, nr_pages);
 533         else
 534                 return set_pages_rw(page, nr_pages);
 535 }
 536
 537 static void kexec_mark_crashkres(bool protect)
 538 {
 539         unsigned long control;
 540
 541         kexec_mark_range(crashk_low_res.start, crashk_low_res.end, protect);
 542
 543         /* Don't touch the control code page used in crash_kexec().*/
 544         control = PFN_PHYS(page_to_pfn(kexec_crash_image->control_code_page));
 545         /* Control code page is located in the 2nd page. */
 546         kexec_mark_range(crashk_res.start, control + PAGE_SIZE - 1, protect);
 547         control += KEXEC_CONTROL_PAGE_SIZE;
 548         kexec_mark_range(control, crashk_res.end, protect);
 549 }
 550
 551 void arch_kexec_protect_crashkres(void)
 552 {
 553         kexec_mark_crashkres(true);
 554 }
 555
 556 void arch_kexec_unprotect_crashkres(void)
 557 {
 558         kexec_mark_crashkres(false);
 559 }
 560
 561 /*
 562  * During a traditional boot under SME, SME will encrypt the kernel,
 563  * so the SME kexec kernel also needs to be un-encrypted in order to
 564  * replicate a normal SME boot.
 565  *
 566  * During a traditional boot under SEV, the kernel has already been
 567  * loaded encrypted, so the SEV kexec kernel needs to be encrypted in
 568  * order to replicate a normal SEV boot.
 569  */
 570 int arch_kexec_post_alloc_pages(void *vaddr, unsigned int pages, gfp_t gfp)
 571 {
 572         if (sev_active())
 573                 return 0;
 574
 575         /*
 576          * If SME is active we need to be sure that kexec pages are
 577          * not encrypted because when we boot to the new kernel the
 578          * pages won't be accessed encrypted (initially).
 579          */
 580         return set_memory_decrypted((unsigned long)vaddr, pages);
 581 }
 582
 583 void arch_kexec_pre_free_pages(void *vaddr, unsigned int pages)
 584 {
 585         if (sev_active())
 586                 return;
 587
 588         /*
 589          * If SME is active we need to reset the pages back to being
 590          * an encrypted mapping before freeing them.
 591          */
 592         set_memory_encrypted((unsigned long)vaddr, pages);
 593 }